import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main1 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str1 = in.nextLine();
        String str2 = in.nextLine();
        StringBuffer ret = new StringBuffer();
        for(int i = 0; i < str1.length(); i++) {
            char ch1 = str1.charAt(i);
            boolean flag = false;
            for(int j = 0; j < str2.length(); j++) {
                char ch2 = str2.charAt(j);
                if(ch1 == ch2) {
                    flag = true;
                    break;
                }
            }
            if(!flag) {
                ret.append(ch1);
            }
        }
        System.out.println(ret);
    }
}